Hundreds of lawyers have marched on Westminster in protest at legal aid cuts as thousands of barristers stage a second walkout at courts in England and Wales.

Janis Sharp, whose son Gary McKinnon narrowly avoided extradition to the United States, Blur drummer-turned-solicitor Dave Rowntree and Paddy Hill, one of the Birmingham Six, were among those speaking at a rally opposite the Houses of Parliament.

Barristers have chosen not to attend proceedings at major crown courts in London, Manchester, Birmingham and Liverpool, among others.

Justice Secretary Chris Grayling is pressing ahead with fee cuts for barristers and solicitors as part of an attempt to slash £220 million from the legal aid budget by 2018/19.

A Ministry of Justice spokeswoman said the final reforms reflect many of the changes barristers and solicitors have asked for and also highlighted measures announced last week to support lawyers through the period of transition.

Many barristers attended the protest outside Parliament dressed in full wig and gowns.

At the Old Bailey, only five out of 18 of the criminal courts were sitting today. The hacking trial and that of Nicky Jacobs for the murder of Pc Keith Blakelock were among those to resume on Monday.

The entrance to the historic court near St Paul's Cathedral in central London, normally crowded with camera crews and photographers, appeared unusually quiet.

Nigel Lithman, chairman of the Criminal Bar Association (CBA), said: "If these cuts are not addressed, then the British justice system, which is held in such high esteem around the world, will cease to exist as we know it and the British public can no longer expect true justice to be delivered.

"It is simply expected that the criminal Bar will accept cuts unparalleled in any other sector of the wider community.

"The Bar cannot and will not accept these unnecessary and crippling cuts and will continue to fiercely oppose them at every opportunity until our reasonable requests have been met with the appropriate levels of consideration."

Barristers refused to attend court for the first time in January, causing widespread disruption to criminal justice.

There are already a number of crown court cases emerging in which defendants have been unable to secure a barrister.

LCCSA president Nicola Hill said: "These cuts mean that law firms will rapidly go to the wall in their hundreds, leaving people who can't afford to pay privately with only the crumbs of legal aid. Firms will sack experienced, more expensive solicitors, replacing them with those who are unqualified and cheap.

"This can only be damaging for justice. The solicitors who are still in business quite simply won't have the time, money or expertise to prepare cases properly.

"And it's the ordinary people, those we don't hear about, who don't make the headlines, who will have to accept third-rate advice. Not the wealthy, who can pay privately."

The Ministry of Justice has previously said it is vital to scale back "one of the most expensive" legal aid schemes in the world and insisted it will remain ''very generous'' even after the changes.

But the CBA said many junior barristers face rates as low as £20 a day, once the hours of preparation, time in court and chambers' fees are factored in, as well as receiving no holiday pay, no pension provision and no sickness or maternity benefits.

A Ministry of Justice spokeswoman said: "At around £2 billion a year, we have one of the most expensive legal aid systems in the world.

"As everybody knows, this Government is dealing with an unprecedented financial challenge and the MoJ has no choice but to significantly reduce the amount of money it spends every year.

"We have spoken at length over the past year with solicitors and barristers about the reforms and our final plans reflect many of the changes they asked for.

"It does mean fee reductions, but it also includes a series of measures to ease their effect on lawyers.

"In line with our efforts to apply the highest fee reductions to the highest earners, these plans represent an average 2% reduction for barristers at the lower end of the fee income scale, and an average 6% reduction more generally."

A number of cases were disrupted at Manchester Crown Court as defence lawyers failed to turn up to represent their clients.

One plea hearing was put back to later this month for a case involving 12 defendants.

Three of the accused appeared via videolink from prison but three others were produced from custody to appear in the court.

Judge Andrew Blake explained to the defendants that they had not seen their lawyers because of the protest against Government cuts.

He said: "I regret that these cases will have to be adjourned. On that date you will all be represented.

"I am sorry that this has happened but it cannot be helped."

The next plea hearing involving two Romanian defendants, who both needed a translator, was postponed until next week because they had no legal representation.

Both were in custody but one was produced in court.

Another hearing involving a retired senior police officer accused of rape did go ahead, as he was represented by the solicitor in his case as a trial date was fixed.

Speaking outside Parliament, Ms Sharp said: "I'm down here because my son Gary McKinnon was fighting extradition for 10 years and without legal aid he wouldn't be here and without legal aid he would be dead."

Ms Sharp said she feared smaller high-street solicitors would be forced to close in the face of reduced fees.

"So when someone comes knocking on the door and says 'we want you' and they might be the most powerful people in the world ... and you walk into a place on the high street ... and they say 'no, sorry, we can't help you' - that's the reality, that's why we are fighting for this."

She added: "Everyone at some time in their life has to go to a solicitor."